Fix reading dicom series error in ITKReader

monai/data/image_reader.py

@@ -244,6 +244,7 @@ def read(self, data: Sequence[PathLike] | PathLike, **kwargs):
                 series_identifier = series_uid[0] if not self.series_name else self.series_name
                 name = names_generator.GetFileNames(series_identifier)
 
+                name = name[0] if len(name) == 1 else name  # type: ignore
                 _obj = itk.imread(name, **kwargs_)
                 if self.series_meta:
                     _reader = itk.ImageSeriesReader.New(FileNames=name)
@@ -631,7 +632,7 @@ def _get_meta_dict(self, img) -> dict:
 
         if self.prune_metadata:
             prune_metadata = {}
-            for key in ["00200037", "00200032", "52009229", "52009230"]:
+            for key in ["00200037", "00200032", "00280030", "52009229", "52009230"]:
                 if key in metadata.keys():
                     prune_metadata[key] = metadata[key]
             return prune_metadata
@@ -661,7 +662,9 @@ def _get_affine(self, metadata: dict, lps_to_ras: bool = True):
         rx, ry, rz, cx, cy, cz = metadata["00200037"]["Value"]
         # "00200032" is the tag of `ImagePositionPatient`
         sx, sy, sz = metadata["00200032"]["Value"]
-        dr, dc = metadata.get("spacing", (1.0, 1.0))[:2]
+        # "00280030" is the tag of `PixelSpacing`
+        spacing = metadata["00280030"]["Value"]
+        dr, dc = metadata.get("spacing", spacing)[:2]
         affine[0, 0] = cx * dr
         affine[0, 1] = rx * dc
         affine[0, 3] = sx
@@ -670,7 +673,7 @@ def _get_affine(self, metadata: dict, lps_to_ras: bool = True):
         affine[1, 3] = sy
         affine[2, 0] = cz * dr
         affine[2, 1] = rz * dc
-        affine[2, 2] = 0
+        affine[2, 2] = 1.0
         affine[2, 3] = sz
 
         # 3d

tests/test_load_image.py

@@ -23,12 +23,13 @@
 from parameterized import parameterized
 from PIL import Image
 
+from monai.apps import download_and_extract
 from monai.data import NibabelReader, PydicomReader
 from monai.data.meta_obj import set_track_meta
 from monai.data.meta_tensor import MetaTensor
 from monai.transforms import LoadImage
 from monai.utils import optional_import
-from tests.utils import assert_allclose
+from tests.utils import assert_allclose, skip_if_downloading_fails, testing_data_config
 
 itk, has_itk = optional_import("itk", allow_namespace_pkg=True)
 ITKReader, _ = optional_import("monai.data", name="ITKReader", as_type="decorator")
@@ -159,6 +160,25 @@ def get_data(self, _obj):
 
 @unittest.skipUnless(has_itk, "itk not installed")
 class TestLoadImage(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        super(__class__, cls).setUpClass()
+        with skip_if_downloading_fails():
+            cls.tmpdir = tempfile.mkdtemp()
+            key = "DICOM_single"
+            url = testing_data_config("images", key, "url")
+            hash_type = testing_data_config("images", key, "hash_type")
+            hash_val = testing_data_config("images", key, "hash_val")
+            download_and_extract(
+                url=url, output_dir=cls.tmpdir, hash_val=hash_val, hash_type=hash_type, file_type="zip"
+            )
+            cls.data_dir = os.path.join(cls.tmpdir, "CT_DICOM_SINGLE")
+
+    @classmethod
+    def tearDownClass(cls):
+        shutil.rmtree(cls.tmpdir)
+        super(__class__, cls).tearDownClass()
+
     @parameterized.expand(
         [TEST_CASE_1, TEST_CASE_2, TEST_CASE_3, TEST_CASE_3_1, TEST_CASE_4, TEST_CASE_4_1, TEST_CASE_5]
     )
@@ -206,6 +226,22 @@ def test_itk_dicom_series_reader(self, input_param, filenames, expected_shape, e
         )
         self.assertTupleEqual(result.shape, expected_np_shape)
 
+    def test_itk_dicom_series_reader_single(self):
+        result = LoadImage(image_only=True, reader="ITKReader")(self.data_dir)
+        self.assertEqual(result.meta["filename_or_obj"], f"{Path(self.data_dir)}")
+        assert_allclose(
+            result.affine,
+            torch.tensor(
+                [
+                    [-0.488281, 0.0, 0.0, 125.0],
+                    [0.0, -0.488281, 0.0, 128.100006],
+                    [0.0, 0.0, 1.0, -99.480003],
+                    [0.0, 0.0, 0.0, 1.0],
+                ]
+            ),
+        )
+        self.assertTupleEqual(result.shape, (16, 16, 1))
+
     def test_itk_reader_multichannel(self):
         test_image = np.random.randint(0, 256, size=(256, 224, 3)).astype("uint8")
         with tempfile.TemporaryDirectory() as tempdir:
@@ -231,6 +267,17 @@ def test_dicom_reader_consistency(self, filenames):
             np.testing.assert_allclose(pydicom_result, itk_result)
             np.testing.assert_allclose(pydicom_result.affine, itk_result.affine)
 
+    def test_dicom_reader_consistency_single(self):
+        itk_param = {"reader": "ITKReader"}
+        pydicom_param = {"reader": "PydicomReader"}
+        for affine_flag in [True, False]:
+            itk_param["affine_lps_to_ras"] = affine_flag
+            pydicom_param["affine_lps_to_ras"] = affine_flag
+            itk_result = LoadImage(image_only=True, **itk_param)(self.data_dir)
+            pydicom_result = LoadImage(image_only=True, **pydicom_param)(self.data_dir)
+            np.testing.assert_allclose(pydicom_result, itk_result.squeeze())
+            np.testing.assert_allclose(pydicom_result.affine, itk_result.affine)
+
     def test_load_nifti_multichannel(self):
         test_image = np.random.randint(0, 256, size=(31, 64, 16, 2)).astype(np.float32)
         with tempfile.TemporaryDirectory() as tempdir:

tests/testing_data/data_config.json

@@ -79,6 +79,11 @@
             "url": "https://github.com/Project-MONAI/MONAI-extra-test-data/releases/download/0.8.1/CT_2D_head_moving.mha",
             "hash_type": "sha256",
             "hash_val": "a37c5fe388c38b3f4ac564f456277d09d3982eda58c4da05ead8ee2332360f47"
+        },
+        "DICOM_single": {
+            "url": "https://github.com/Project-MONAI/MONAI-extra-test-data/releases/download/0.8.1/CT_DICOM_SINGLE.zip",
+            "hash_type": "sha256",
+            "hash_val": "a41f6e93d2e3d68956144f9a847273041d36441da12377d6a1d5ae610e0a7023"
         }
     },
     "videos": {